Electrical installation Basics:

Electrical installation and electrical work

Electrical installation Basics:: voltage

Smaller electrical installations can be done by DIYers themselves. Therefore, you will find here the basics of electrical engineering, starting with questions about what electricity actually is, about definitions of direct or alternating current, voltage and resistance up to fuses, degrees of protection and a small lexicon with technical terms.

In addition, we present here the most important tools for electrical work. However, for safety reasons, an electrician must be commissioned to carry out more complex work.

Safety takes precedence!

Electrical installation Basics:: basics

Warning symbol electrical voltage

Be sure to read the following safety instructions before installing electrical wiring:

  • Before starting work, always switch off the power at the fuse box. This is done either by switching off the corresponding fuse or by unscrewing it. For safety, tape over it to ensure accidental turn-on by another person.
  • For your own safety, measure whether the cable is really de-energized.
  • For appliances or lights, turn them off and unplug the power cord.
  • Work on high current connections, main fuses, bad counters and house connection may only be carried out by trained specialists, ie. H. Electrician, make.
  • Never touch metal parts or uninsulated wires, even when the device is fully switched off, as the parts and lines mentioned store electrical energy.
  • Defective devices should be disconnected immediately, for example by unplugging the power plug.
  • Damaged cables and plugs must not be repaired, but should be replaced by a specialist.
  • If changes to the electrical wiring are planned, an electrician should be called in to carry out the work and dismantle completed installations.
  • Only use approved materials for electrical installations, identifiable by VDE certification and the GS seal.
  • For children in the household sockets should be equipped with child safety devices.

For electrical work and installation, it is always the contractor's responsibility to ensure that the work is carried out VDE guidelines be performed. If an accident occurs due to improper work, it is the person responsible who last worked on the electrical system or the device.

Fundamentals of electrical engineering

What is electricity?

Electrical installation Basics:: conductor

As electric current is the Movement of charge carriers called, for example, by a power cable run in the house wall. So that the current will be flowingdifferently charged bodies needed. Only then does an electric field arise.

If one separates the charge bodies, as happens for example in a car battery by chemical processes or in an electric generator by mechanical movement, they are moved, more precisely: They are accelerated, At this moment, electricity is flowing.

How does the electricity get into the house?

High voltage power lines carry the electricity from the power plant to transformer stationswhere it is transformed down to a consumer-rated voltage of 230 or 400 volts. After that, the electricity arrives via ground or overhead lines to the house connection boxes.

From there, the main line leads to the main fuses. Through the meter cabinet it goes on to the power distribution. There are the Housing and house fuses, each of which safeguards its own circuit. Each circuit leads to the so-called "stationary" consumers, these are switches and sockets.

Accordingly, one designates electrical devices, such as kettles or laptops as "mobile" consumers, Only after the counter, which is the property of the respective power plant, the electrician may make changes.

What is a circuit?

Be in an electrical circuit one or more electrical energy sources interconnected with different electrical components, for example, a battery with a light bulb. In a closed circuit, a charge transport is possible, so that the lamp lights up.

In a broken circuit this is not the case: the lamp stays off. The electricity from the outlet at home is AC. however, a battery is DC.

What is AC?

The electricity is divided into alternating current and direct current.
The term "AC" is based on the fact that he is curved constantly moved from plus to minus, The speed of this vibration, d. H. the frequency is given in Hertz (Hz).

A hertz means one oscillation, ie two changes of direction per second.

The usual in German households 230/400 V ac has a frequency of 50 Hz. The house connection is up to the counter generally as 400-V three-phase power line laid. This consists of three current-carrying conductors, the so-called outer conductors (symbols: L1, L2 and L3), a center conductor (also called neutral conductor, abbreviation: N) and the protective conductor (abbreviation: PE).

The outer conductors carry a mutually shifted alternating voltage. The return of a current from the outer conductors via the center conductor. 230-V ac is applied when only one of the outer conductors and the neutral conductor is used. More information about the markings of cables and the color codes of the conductors gives the advice page cables.

What is DC?

AC out of the socket can be done with a transformer convert to "low power" (DC)who bears no danger to life and limb. DC has no frequency, plus and minus are always constant. It is used, for example, for the safe operation of children's toys or other powered equipment.

Here may the Voltage not more than 24V be. To generate DC voltage from AC voltage, you need power supplies with integrated rectifier.

Current, voltage and resistance

Electrical installation Basics:: voltage

Various resistances

Current only flows when there is voltage. This size is measured in Volt (V), Electrical voltage is comparable to the pressure in a water pipe, which is a prerequisite for water to flow.

The amperage you get in Amps (A) depends on the line resistance that is in Ohms (Ω) is measured. Is the resistance big, only little electricity flows. It is all the higher, the thinner the cross-section and the higher the so-called resistivity of the conductor.

As the resistance increases, so does the temperature. This effect is made use of in hotplates or the filament of a lamp. Undesirable and dangerous is the Resistance-induced warming in the supply lines to consumers. It is essential to ensure that the cable cross-sections correspond to the maximum power consumption of the connectable consumers.

With Watts (W) is the amount of electricity consumed by a device or a lamp. 1000 watts are 1 Kilowatts (kW).

Current, voltage and resistance are closely related. Power can and should only flow when the poles of a voltage source are connected to each other via the resistance of the electrical load. This resistance then determines the amount of current.


Electrical installation Basics:: conductor

Screw fuses and circuit breakers in the fuse box

Flows more electricity through a pipe than it can transport without heat damage, the current flow must be prevented, That's the job of backups. There are two types of so-called overcurrent protection devices: automatic circuit breakers and fuses.

Breakers, also Circuit breaker called, are used today predominantly. If overloaded, they will open a switch, breaking the circuit. This will allow you to turn them on again after the fault has been eliminated. The replacement of circuit breakers may only be done by an electrician.

fuses burn through when an overload occurs, and must be replaced afterwards. In the form of screw type These fuses are often found next to circuit breakers in the fuse box.

These low-voltage fuses belong to the D system or the newer D0 system, where the fuse link and the screw cap are disconnected. You can also replace fuses yourself by screwing in a new fuse cartridge. Nevertheless, it is advisable to explore in doubt with an electrician.

Protection classes and protection classes against enclosure voltage

If a device is connected to a power outlet, current flows from the outer conductor to the neutral conductor. The protective conductor is connected via contact strips on the plug and metal tongues to the socket with electrically conductive housing parts. Without the connected protective conductor, the entire device housing would be liveif a defective outer conductor would come into contact with electrically conductive housing parts.

If, for example, plugs do not have such a protective contact, the connected devices must be particularly insulated. Here there are three protection classesthat indicate how a device is protected against case voltage:

protection classsymbolstatement
Protection class 1 (protective conductor)Circle with a vertical line inside, below which are two shorter lines.All electrically conductive housing parts must be connected to the protective conductor or the earth conductor of a fixed electrical installation.
Protection class 2 (protective insulation)Square, in which a smaller square liesDevices have reinforced insulation that protects against contact with live parts. There is no connection to a protective conductor.
Protection class 3 (safety extra-low voltage SELV / PELV)Rhombus with three vertical linesDevices with AC voltage below 50 V or below 120 V DC run on a safety extra-low voltage and have a reinforced insulation during mains operation, which protects against contact with live parts. They are powered by smaller generators (eg dynamo), batteries or batteries. They must not be earthed or connected to the protective conductor.

Appliances with Euro plug belong to protection class 2. Depending on the intended use, they must also be protected to varying degrees against the ingress of foreign bodies and water. The respective degree of protection is shown on the device itself with an IP and two digits. What these numbers mean in detail can be found in the following table:

1st code: Foreign body protection2nd code: water protection
IP 0: no protectionIP 0: no protection
IP 1: Foreign body protection> 50 mmIP 1: vertically falling dripping water
IP 2: foreign matter> 12 mmIP 2: sloping dripping water
IP 3: foreign body protection> 2.5 mmIP 3: spraying water
IP 4: Foreign matter> 1 mmIP 4: splash water
IP 5: Dust depositIP 5: jet water
IP 6: Ingress of dustIP 6: flooding
--IP 7: Immersion at a specified pressure
--IP 8: Immersion at elevated pressure

An IP 45 protection device would thus be protected against penetration of foreign bodies larger than 1 mm and water jets.

Tool for testing and measuring

Electrical installation Basics:: basics

Use the can drill to make the recesses for sockets

To carry out electrical installations and repairs yourself, you should get the following basic equipment:

  • nose pliers
  • side cutter
  • Phillips screwdriver
  • Kombinationszange
  • screwdriver
  • A single-pole voltage tester
  • removal pliers
  • Utility knife

If you want to lay pipes under plaster, you also need a hammer or miter, chisel, yardstick, pencil, putty, drill with stone drill and a bell drill or a Hohlwanddosenfräser. On bell drills cuts circular slices of plaster, stone and concrete and is equipped with tungsten carbide cutting edges. The Hollow wall box cutter is the special device for eliminating can openings in plate building materials.

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Video Board: Basic Residential Wiring